Update Char-Arrays Definitions in pgm_textfile_generator

Description:
The current practice lacks clarity regarding null termination, potentially leading to confusion and errors during implementation. To ensure consistent and understandable codepractices, we propose updating all char-array definitions to follow the pattern [STRING_LENGTH+1], explicitly indicating the need for manual null termination.

User Story:
As a developer, I expect char-array definitions in the pgm_textfile_generator to adhere to the pattern [STRING_LENGTH+1], clearly indicating the requirement for manual null termination, facilitating efficient coding and reducing the risk of errors.